Method of making filter material for cigarettes



Jan. 2, 1968 YOSHITARO mouz 3,351,139

METHOD OF MAKING FILTER MATERIAL FOR CIGARETTES Filed Aug. 2, 1965 FLOW SHEET 1. STARTING (UURED) TOBACCO SHREDS 2. WASHING WITH WATER 3. BLEACHING 4. IMPREGNATION WITH AN AN ALUMINUM SALT 5. IMPRE GNATIOM WITH AN A LKALI METAL SILICATE 6. WASHING WITH WATER 7. URYINQ 8. PRODUCT (BLEACHED TOtACCO SHREDS CARRYING ALUMINUM SILICATE THEREON) INVENTOR YOSHITARA INOUTE ATTOR EY United States Patent 3,361,139 METHOD OF MAKING FILTER MATERIAL FOR CIGARETTES Yoshitaro Inoue, 755 3-ch0me, Takada-minamicho, Toshima-ku, Tokyo, Japan Filed Aug. 2, 1965, Ser. No. 476,714 Claims priority, application Japan, Aug. 7, 1964, 39/ 45,037 3 Claims. (Cl. 131-143) ABSTRACT OF THE DISCLOSURE A method of making a filter material useful as a cigarette filter made from tobacco shreds by washing the shreds with water to remove water-soluble components, bleaching the shreds, impregnating the washed, bleached shreds with an aqueous solution of an aluminum salt and thereafter impregnating the same with an aqueous solution of an alkali metal silicate. The filter material, when used as a cigarette filter, removes alkaloids from the cigarette smoke and does not adversely affect the cigarette taste.

This invention relates to a method of making a filter for cigarettes.

Cries have been heard for a long time regarding the harm of smoking. Lately, in view of reports that cigarette was the cause of lung cancer, this harm has at last begun to attract public attention. Nevertheless, that there is a trend towards a year by year increase in the consumption of cigarettes is due to the fact that it is becoming an article of luxury that is indispensable in our daily life. Attempts have already been made to minimize to some extent the harmful effects of tobacco by providing a filter at that end where the mouth is applied in smoking and thus to reduce the amount of harmful substances that are inhaled during smoking. Heretofore, a great variety of products have been proposed for such a filter, but none have been satisfactory. The filter that is in general use at the present time is one composed of acetate fibers. This is being used only for the reason that it can be provided at low cost and that its finish is neat. It has the drawbacks however that its adsorption of the harmful substances is not entirely satisfactory and furthermore that it changes the taste of tobacco. There is also one referred to as a double filter which is composed of two layers, one of acetate fibers and the other of carbon, but neither does this filter give satisfactory results.

I found that when shreds of tobacco leaves or stalks were washed with water, bleached, then dipped in an aqueous solution of a water-soluble aluminum salt fol lowed by removal of the excess liquor, after which the so obtained wet mass of tobacco is contacted with an aqueous solution of alkali silicate and thereafter the intended product is collected, a filter material could be made which when used as a filter of cigarettes, has not only a high alkaloid filtration rate but also does not impair the taste of tobacco.

As the starting material of the invention method, included are the shreds of the leaves of tobacco such as the commercially available cut tobacco, the shreds of the veins of tobacco which are produced as a by-product during the manufacture of cut tobacco, also the shreds of the stalks of tobacco as well as other shreds of tobacco of similar nature. While it is also possible to use as the starting material of the invention method the shreds of other plants such as giant knotweed and eggplants, mixed in with the aforesaid shreds of tobacco, the conjoint use in great amounts of plants other than tobacco is not desirable since a product will be obtained which tends to impair the taste of tobacco. The term shred as herein used refers to a material having a shape whose dimension in one direction is considerably greater than its dimensions in the other two directions. Shreds will also be referred to herein as fibers.

The figure of the drawing is a flow sheet of the steps of the process.

According to the invention method, the shreds of tobacco leaves or stalks are washed in a water whose temperature has been suitably raised and the water soluble components are removed as much as possible. It is preferred that the washing with water and hot water is repeated several times. The water-washed tobacco is submitted to a bleaching operation. Severe bleaching conditions must be avoided as it will destroy the form of the vegetable structure of the tobacco and in consequence yield a powdery product unsuitable for use as a filter. It was found that the bleaching is conveniently carried out at a temperature ranging between room temperature and about 45 C., using chlorine or a chlorine-containing bleaching agent. This mild bleaching can be repeated two or more times. When the bleached tobacco shreds are washed with water and dried, a light yellowish white product is obtained, but since there is a tendency of the individual tobacco fibers-to stick to each other, this product does not have bulk and thus does not yield a filter excelling in filtration rate and in low gas permeation resistance.

The bleached tobacco, after having been washed and squeezed, is submitted to the next operation without being dried. Namely, the bleached tobacco shreds are impregnated with aluminum ions by dipping in a water-soluble aluminum salt, and advantageously in an aqueous solution of aluminum sulfate, followed by removal of the excess liquor. The preferred content of the aluminum ion is about 0.001-1.0% by weight, and particularly about 0.0050.5% by weight, based on the bleached tobacco. If the content of aluminum ion is less than 0.001% by weight, the desired bulk and filtration rate cannot be attained. On the other hand, if the content of aluminum ion is great, the amount of aluminum silicate that forms on the tobacco shreds in a later step becomes excessive, with the consequence that not only is there a. tendency for the tobacco fibers to stick to each other or powderize but also the taste of the tobacco is adversely affected at times. The aluminum ion content will depend upon the concentration and temperature of the water-soluble aluminum salt, the rate of squeezing and the extent of water-washing. In a preferred mode of the present invention, the aluminum ion content coming within the range as herein'before specified can be attained by dipping the bleached tobacco shreds at a temperature of about 60-80 C. in an aqueous solution of about 0.0l-2% by weight of aluminum sulfate to which has been added an alkali agent such as caustic soda or sodium carbonate in an amount of the order as will cause the solution to be slightly turbid, after which the wet tobacco mass is squeezed to a weight two times, and preferably 1.8 times, the weight of the tobacco fibers and, if necessary, by further water-washing and squeezing.

The bleached tobacco fibers, which have been impregnated with the preferred amount of aluminum ions, is then contacted at room temperature or an elevated tem perature with an aqueous solution of alkali silicate, and advantageously sodium silicate. While the concentration of the aqueous solution of alkali silicate is not critical, usually a concentration of about 140% by weight will do. The temperature of this aqueous solution may range from room temperature to C., and preferably about 30 to 50 C. This aqueous solution may contain a small amount of alkaline earth metal silicate, such as calcium silicate, and/or a mineral acid, such as hydrochloric acid. The so obtained product is washed with water and dried.

The so obtained product is very bulky and can yield with about 0.120.16 g. thereof a tip mm. in circumference and 17 mm. in length and having, as a filter for cigarettes, suitable hardness and sufficiently low resistance to gas permeation.

According to the invention method, material for cigarette filters having a very high alkaloid filtration rate can be obtained, as compared with conventional materials which are used for such a purpose. Further, this filtration rate can be readily controlled by controlling the amount of aluminum silicate that is applied to the bleached tobacco. Again, the products of the invention method not only do not adversely affect the taste of tobacco but rather have the effect of improving it. In addition, the invention method has such merits from the economic standpoint as that the waste materials obtained during the manufacture of cigarettes, such as the veins and stalks of tobacco, can be used as the starting material, and also the method is suited to large-scale operations. Further, as the products of the invention method have the property of being self-acting as a fire extinguisher, there is no danger of its becoming the cause of fires due to carelessness.

The products of the invention method can be formed independently in the form of a plug or a rod, then cut into tips and attached to cigarettes. They also can be mixed with the conventional filtering agents and then be made into a plug, rod or tip. Alternatively, they can be used in a tip of composite layers, one of which consists of the invention filtering agent.

Example 1 One package g.) of commercially available Minori (cut tobacco i.e., Japanese pipe tobacco, sold by the Japanese Monopoly Ofiice) is placed in a 3-liter beaker and Washed several times with pure water. After dehydration, 1 liter of hot water is added to the tobacco being treated, which is then allowed to stand for 20-30 minutes, following which the water-washing and hot water treatment is again repeated to remove as much as possible those substances which are soluble in water. This hot Water treatment is effective in removing to a still greater degree the water-soluble substances than when treatment is by water alone.

Next, a 5-liter beaker is filled with ca. C. hot water, to which are added 6 g. of bleaching powder containing 60% available chlorine, followed by stirring. Then the foregoing tobacco being treated is introduced into the beaker and several minutes later 4 g. of sodium carbonate are added and stirred. Fifteen minutes later, 4 g. of the aforementioned bleaching powder are added and by further addition of 2 g. of sodium carbonate, the bleaching treatment is carried out. The tobacco whose bleaching treatment has been completed is removed of its chlorine content by thoroughly washing with water and is then dehydrated.

Next, 1 liter of aluminum sulfate aqueous solution of about 5 degrees Baum is placed in a 3-liter beaker, to which are then gradually added with stirring 300' cc. of sodium carbonate aqueous solution of about 65 degrees Baum. The foregoing bleached tobacco is then introduced into this solution, followed by stirring and gradually heating to about 70 C. at which temperature the heating is stopped and the solution containing the tobacco being treated is allowed to stand for 30 minutes while kept Warm. The tobacco is then washed with water several times and squeezed to remove its excess liquor. The so obtained wet mass of tobacco impregnated with aluminum sulfate (partly converted to aluminum hydroxide) contains 0.85% by weight of Al based on the bleached tobacco.

Next, this wet mass of tobacco is placed in a 3-liter beaker containing 1 liter of sodium silicate aqueous solution of about 5 degrees Baum, after which the solution containing the tobacco mass is gradually heated to about 40 C. at which temperature the heating is stopped, and while being kept warm it is allowed to stand for about 10 minutes. Then the tobacco mass is washed thoroughly with water, dehydrated and dried to yield 30 g. of the intended filter material.

The filter material obtained in the hereinabove described manner, after being rolled and formed by a cigarette machine, is cut into filter length and used by being attached to mouthpiece of cigarettes. About 200 filter tips of 17 mm. length, the length of the tips of the usual commercial cigarettes, can be obtained from the foregoing amount of filter material.

Example 2 Filter-tipped cigarettes were prepared by attaching a composite tip consisting of a tip (17 mm. long containing 0.130 g. of filter material) made from the invention filter material obtained in Example 1 and an acetate fiber tip 3 mm. long, to one end of cigarettes 63 mm. long and 25 mm. in circumference (content of tobacco 0.90 g.). A smoke suction test of these cigarettes was conducted employing an automatic smoke sucker and using the following smoke sucking conditions:

Time per each smoke suck seconds 2 Interval between each smoke suck do 30 Speed of smoke suction ml./sec 20 Volume per each smoke suck ml 40 Smoke suction length mm 50 The alkaloid (nicotine) in the main smoke stream was captured using a Cambridge filter CM113, a filter made from glass fibers suitable for use in the determination of particulate matters in aerosols produced by the Cambridge Filter Corporation, Syracuse, N.Y., and sold by Phipps and Bird, Inc., Richmond, Va. Smoke from 5 cigarettes was sucked in succession in each smoke suction test. In other words, one Cambridge filter was used for sucking the smoke from 5 cigarettes. The nicotine content (A of the sample filter tips and the total nicotine content (A of the Cambridge filter and acetate tips were determined using a photoelectric spectrometer. The filtration rate E(N)% of the sample filter material was calculated by substituting the values A and A in the following equation:

Example 3 Three species of cigarettes (A), (B) and (C) Were pre pared: (A) being a cigarette without a filter; (B), the cigarette (A) fitted with a commercial acetate filter; and (C), the cigarette (A) with A1 of tip (B) replaced with a tip made of the product obtained in Example 1. These were then submitted to a smoking test by thirty smokers, all of whom were smokers having more than 15 years of experience. This test was for finding the smoking satisfaction obtainable by these smokers from the cigarettes prepared as hereinabove described. The test was conducted with the intermediary of a cigarette holder without informing the smokers as to which species they were smoking. Twenty-seven of the thirty smokers indicated that the order of smoking satisfaction was C, A, B while three of the smokers indicated that it was A, C, B.

I claim:

1. A method of making a filter material for cigarettes which comprises the steps of washing shreds of tobacco leaves or stalks with water, bleaching the shreds, dipping the shreds in an aqueous solution of a Water-soluble aluminum salt, followed by removing the excess liquor, then contacting the resulting Wet mass With an aqueous solution of alkali silicate and thereafter collecting the intended product.

2. The method according to claim 1 wherein said Wet mass of bleached tobacco to be contacted With said aqueous solution of alkali silicate contains as Al about 0.001 to 1.0% by Weight of an aluminum salt, based on the bleached tobacco.

3. A method of making a filter material for cigarettes which comprises the steps of Washing shreds of tobacco leaves and stalks with Water, bleaching the shreds, dipping the shreds in an aqueous solution of aluminum sulfate, followed by removing the excess liquor, thereby to render References Cited UNITED STATES PATENTS 1,972,718 9/1934 Sharlit 131-143 X 2,131,160 9/1938 Avedikian 131-142 X 2,525,785 10/ 1950 Feinstein et al.

FOREIGN PATENTS 32,759 5/ 1934 Netherlands.

LUCIE H. LAUDENSLAGER, Primary Examiner. 

